Reference UserForm Textbox

I'm building a UserForm that has several TextBoxes to gather basic project information to fill in the header of a report. The first TextBox is the Job #... I'm trying to implement code for an "Auto Fill" button (based on working VBA code from another workbook) that will fill the other TextBoxes in the UserForm...
The working VBA code from the other workbook does "Auto Fill" for Worksheet Ranges, not UserForm TextBoxes. How should I reference the UserForm Textboxes in the code to specify their value?

Workbooks("Template Generator.xls").Forms("ProjectInfo").Activate
If TextBox("InptJobNum").Text = "" Then
MsgBox "Please Insert Job Number"
TextBox("InptJobNum").Select
Exit Sub
Else
Jnum = TextBox("InptJobNum") 'Specify Job Number
Workbooks("Job Log.xls").Sheets("Job Log").Activate
End If
If WorksheetFunction. CountIf(Range("A2:A1000"), Jnum) = 0 Then
Workbooks("Template Generator.xls").Forms("ProjectInfo").Activate
MsgBox "Invalid Job Number, or cannot be located... Please correct and try again"
TextBox("InptJobNum").Select
Exit Sub
End If